Protects against motor overspeeding due to unintended excessive field weakening.
The field weakening loop reduces the field current to achieve speed control above base speed. At top speed the field reaches a minimum value. MIN
FIELD CURRENT should be set below this minimum value to allow reasonable margin for transient control near the top speed but not lower than
6% as this could then cause the "Field Fail" alarm to operate.
Maximum volts is the back-emf voltage level at which field weakening begins. It is also known as "Spillover Bias". The default value is 100% of the
nominal value as set by the armature voltage calibration value. This value might be reduced due to the known IR drop included in the armature
voltage calibration value. Additionally for commissioning purposes, this value may be set to another (lower) desirable level, and subsequently
returned to the original value.
This is the lead time constant of the back emf feedback filter which is used for reducing armature voltage overshoots when accelerating fast through
base speed with a default of 100 (ms).
Refer to Chapter 5: "Control Loops" for details of Tuning.
BEMF FBK LAG 192 20 to 5000
This is the lag time constant of the above feedback filter. If the filter is active, the ratio of lead / lag should always be greater than 1 to give an overall
lead action which reduces the voltage overshoot and less than, typically, 3 for stable control. The default values cancel each other and make the filter
inactive with a default of 100 (ms).
Refer to Chapter 5: "Control Loops" for details of Tuning.
FLD. QUENCH DELAY 185 0.0 to 600.0 s
If dynamic breaking is used the field must be maintained for a period after the drive is disabled until the motor reaches zero speed. The field quench
delay is the period of time that the field is maintained for when the drive is disabled.
FLD. QUENCH MODE 186 QUENCH / STANDBY
After the field quench delay has expired, the field can be entirely quenched or put into a standby mode at 50% of rated current or volts depending
whether in current or voltage control mode respectively. (The default standby value of 50% can be modified through the "SYSTEM / Reserved"
Menu which is primarily for factory use only and requires the “super” password.)
Threshold for UP TO FIELD diagnostic as a percentage of calibrated field current (see below).
FLD. CTRL MODE 209 See below
Selects between open-loop VOLTAGE CONTROL or closed-loop CURRENT CONTROL.
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